Composition and method for low temperature deposition of silicon-containing films such as films including silicon nitride, silicon dioxide and/or silicon-oxynitride

ABSTRACT

Silicon precursors for forming silicon-containing films in the manufacture of semiconductor devices, such as low dielectric constant (k) thin films, high k gate silicates, low temperature silicon epitaxial films, and films containing silicon nitride (Si 3 N 4 ), siliconoxynitride (SiO x N y ) and/or silicon dioxide (SiO 2 ). The precursors of the invention are amenable to use in low temperature (e.g., &lt;500° C.) chemical vapor deposition processes, for fabrication of ULSI devices and device structures.

FIELD OF THE INVENTION

[0001] The present invention relates generally to the formation ofsilicon-containing films in the manufacture of semiconductor devices,and more specifically to compositions and methods for forming suchfilms, e.g., films comprising silicon, silicon nitride (Si₃N₄),siliconoxynitride (SiO_(x)N_(y)), silicon dioxide (SiO₂), etc., lowdielectric constant (k) thin silicon-containing films, high k gatesilicate films and low temperature silicon epitaxial films.

DESCRIPTION OF THE RELATED ART

[0002] In semiconductor manufacturing, thin (e.g., <1,000 nanometersthickness) passive layers of chemically inert dielectric materials, suchas silicon nitride (Si₃N₄), siliconoxynitride (SiO_(x)N_(y)) and/orsilicon dioxide (SiO₂), are widely employed in microelectronic devicestructures, to function as structural elements of the multi-layeredstructure, such as sidewall spacer elements, diffusion masks, oxidationbarriers, trench isolation coatings, inter-metallic dielectricmaterials, passivation layers and etch-stop layers.

[0003] Deposition of silicon-containing films by chemical vapordeposition (CVD) techniques is a highly attractive methodology forforming such films. CVD processes involving low deposition temperaturesare particularly desired, e.g., temperatures less than about 550° C.,but require the availability and use of suitable precursor compositionsfor such purpose.

[0004] Precursors suitable for the formation of dielectricsilicon-containing films on semiconductor substrates at lowtemperatures, e.g., less than about 550° C., must meet the followingcriteria:

[0005] (1) be highly volatile, with liquids having boiling points <250°C. at atmospheric pressure being generally preferred, since higherboiling points make delivery of the precursor disproportionately moredifficult for the intended application;

[0006] (2) be thermally stable and less hazardous, relative to silanes,disilane and polysilanes, including silicon source compounds such astrichlorosilane and hexachlorodisilane;

[0007] (3) have minimum halogen content, to correspondingly minimizeformation of particulates and clogging of CVD system pumps by solidbyproducts such as quaternary ammonium salts;

[0008] (4) preferably be free of direct Si—C bonds, to correspondinglyminimize carbon contamination of the product films;

[0009] (5) be free of pyrophoricity as well as any susceptibility todetonation and/or rapid decomposition during storage;

[0010] (6) preferably have reactive sites consistent with low activationenergies in the case of silicon nitride deposition; and

[0011] (7) have stable organic ligands providing sustained resonancetime on the substrate surface to provide high conformality anduniformity of the deposited film, with the organo moiety subsequentlybeing readily liberated, e.g., by a decomposition pathway or co-reactionwith another species.

[0012] As an example of the foregoing considerations,hexachlorodisilane, Cl₃Si—SiCl₃, might on initial consideration appearto be a suitable candidate precursor for CVD formation of silicon oxide,silicon oxynitride and/or silicon nitride thin film structures, since itpossesses a weak silicon-silicon bond, rendering it ostensibly amenableto use at low CVD process temperatures, but such compound is reported tooxidatively decompose to a shock-sensitive material, and shock,long-term storage and/or high temperature handling may result inspontaneous detonation of the compound. Such adverse potential effectstherefore cause hexachlorodisilane to be less preferred for use as asilicon-containing film precursor for forming silicon-containing films,e.g., of silicon oxide, silicon oxynitride and/or silicon nitride, on asubstrate.

[0013] Among silicon-containing films, silicon nitride poses particularproblems. Silicon nitride deposition at temperatures below 500° C. hasattracted particular interest for fabrication of microelectronic devicestructures, such as diffusion barriers, etch-stop layers and side-wallspacers, with tight geometric characteristics and reduced feature size(<130 nanometers). For the next generation of ultra-large scaleintegration (ULSI) devices, deposition precursors and processes aredesired that accommodate deposition of silicon nitride films attemperatures not exceeding about 450° C. Currently used precursors,e.g., BTBAS or silane/ammonia, typically require temperatures above 600°C. to form high quality Si₃N₄ films.

[0014] The art therefore has a continuing need for improved precursorsamenable to deposition methods such as chemical vapor deposition, forforming silicon-containing films of the aforementioned types.

SUMMARY OF THE INVENTION

[0015] The present invention relates generally to the formation ofsilicon-containing films in the manufacture of semiconductor devices,and more specifically to compositions and methods for forming suchsilicon-containing films, such as films comprising silicon, siliconnitride (Si₃N₄), siliconoxynitride (SiO_(x)N_(y)), silicon dioxide(SiO₂), etc., silicon-containing low k films, high k gate silicates, andsilicon epitaxial films.

[0016] The present invention in one aspect relates to a silicon compoundselected from the group consisting of:

[0017] (A) compounds of the formula:

[SiX_(n)(NR¹R²)_(3-n)]₂  (1)

[0018] wherein:

[0019] R¹ and R² may be the same as or different from one another andeach is independently selected from the group consisting of H, C₁-C₅alkyl, and C₃-C₆ cycloalkyl;

[0020] X is selected from the group consisting of halogen (e.g.,bromine, fluorine and chlorine), hydrogen and deuterium; and

[0021] 0≦n≦2;

[0022] (B) compounds of the formula

[0023] wherein:

[0024] each of R₃ can be the same as or different from the other andeach is independently selected from the group consisting of H, C₁-C₄alkyl, and C₃-C₆ cycloalkyl; and

[0025] each of R₄, R₅ and R₆ can be the same as or different from theothers and each is independently selected from the group consisting ofH, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, Si(CH₃)₃ and SiCl₃;

[0026] (C) metal source reagent complexes formed by metal cationreaction with deprotonated anionic forms of the compounds (B);

[0027] (D) disilicon cycloamides of the formulae (3)-(6):

[0028] wherein:

[0029] each of R₈ can be the same as or different from the others andeach is independently selected from the group consisting of H, C₁-C₄alkyl, and C₃-C₆ cycloalkyl; and

[0030] each of R₉ can be the same as or different from the others andeach is independently selected from the group consisting of H and NR₈Hwhere R₈ is as defined above; and

[0031] (E) cyclosilicon compounds of the formula:

[0032] wherein:

[0033] each of R₁₀ and R₁₁ can be the same as or different from theothers and each is independently selected from the group consisting ofH, C₁-C₄ alkyl, and C₃-C₆ cycloalkyl.

[0034] In another aspect, the invention relates to a method of forming asilicon-containing film on a substrate, comprising contacting asubstrate under chemical vapor deposition conditions includingtemperature below 600° C. with a vapor of a silicon compound of a typeas described above.

[0035] Another aspect of the invention relates to a method of making asilicon compound of the formula

[SiX_(n)(NR¹R²)_(3-n)]₂  (1)

[0036] wherein:

[0037] R¹ and R² may be the same as or different from one another andeach is independently selected from the group consisting of H, C₁-C₅alkyl, and C₃-C₆ cycloalkyl;

[0038] X is selected from the group consisting of halogen (e.g.,bromine, fluorine and chlorine), hydrogen and deuterium; and

[0039] 0≦n≦2,

[0040] such method comprising reacting a disilane compound of theformula X₃Si—SiX₃ with an amine (R¹R²NH) or lithium amide ((R¹R²N)Licompound, wherein X, R¹ and R¹ are as set out above, according to areaction selected from the group consisting of the following reactions:

[0041] A still further aspect of the invention relates to a method offorming a metal, metal nitride or metal oxide film on a substrate,comprising contacting said substrate with a precursor metal complexformed by ionic reaction of metal cation with a deprotonated anionicform of a silicon compound of the formula (2) above, e.g., a compoundsuch as

[0042] wherein each of the R substituents may be the same as ordifferent from the other and each is independently selected from thegroup consisting of H, C₁-C₄ alkyl, and C₃-C₆ cycloalkyl.

[0043] Yet another aspect of the invention relates to a method offorming a silicon nitride film on a substrate by chemical vapordeposition, comprising contacting said substrate with vapor of siliconsource and nitrogen source compounds, wherein said nitrogen sourcecompounds are other than nitrogen or ammonia, and said chemical vapordeposition is conducted at temperature <550° C., wherein said nitrogensource compound is selected from the group consisting of R-diazocompounds, wherein R is H, C₁-C₄ alkyl or C₃-C₆ cycloalkyl, triazoles,tetrazoles, amadines, silylazides, small ring nitrogen compounds, andmolecules including organic acyclic or cyclic moieties that contain oneor more —N—N bonds.

[0044] Still another aspect of this invention relates to a method offorming a silicon epitaxial layer on a substrate at low temperature,e.g., a temperature below about 600° C., and preferably below 550° C.,by contacting the substrate with a silicon precursor in the presence ofa substantial excess of a reducing agent, such as hydrogen, silane(SiH₄) or disilane (Si₂H₆).

[0045] Other aspects, features and embodiments of the invention will bemore fully apparent from the ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0046]FIG. 1 is an ¹H NMR spectrum of (HNEt)₃Si—Si(HNEt)₃.

[0047]FIG. 2 is a ¹³C NMR spectrum of (HNEt)₃Si—Si(HNEt)₃.

[0048]FIG. 3 is an STA plot for (HNEt)₃Si—Si(HNEt)₃.

[0049]FIG. 4 is an ¹H NMR spectrum of (Bu^(t)NH)₂ClSi—SiCl(HNBu^(t))₂.

[0050]FIG. 5 is a ¹³C NMR spectrum of (Bu^(t)NH)₂ClSi—SiCl(HNBu^(t))₂.

[0051]FIG. 6 is an STA plot for (Bu^(t)NH)₂ClSi—SiCl(HNBu^(t))₂.

[0052]FIG. 7 is an ¹H-NMR spectrum of (Bu^(t)NH)₂Si(H)Cl in C₆D₆.

[0053]FIG. 8 is an ¹H-NMR spectrum ofη-(N,N-t-butyl)-di(t-butylamino)cyclodisilane in C₆D₆.

[0054]FIG. 9 is an STA plot forη-(N,N-t-butyl)-di(t-butylamino)cyclodisilane.

[0055]FIG. 10 is a plot of deposition rate as a function of temperaturefor (HNEt)₃Si—Si(HNEt)₃ at 10 torr, 10 seem NH₃, 10 seem He, and 0.1ml/minute.

[0056]FIG. 11 is a plot of deposition rate as a function of temperaturefor (NEt₂)₂ClSi—SiCl(NEt₂)₂ at 10 torr, 10 sccm NH₃, 10 sccm He, and 0.2ml/minute.

[0057]FIG. 12 is a plot of deposition rate as a function of temperaturefor cyclotrimethylene-bis(t-butylamino)silane at 10 sccm NH₃, 10 sccmHe, and 0.2 ml/minute.

[0058]FIG. 13 is a plot of deposition rate as a function of temperatureη-(N,N-t-butyl)-di(t-butylamino)cyclodisilane at 10 torr, 10 sccm NH₃,10 sccm He, and 0.2 ml/minute.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF

[0059] The present invention relates to silicon precursors for CVDformation of films on substrates, such as silicon precursors for forminglow k dielectric films, high k gate silicates, low temperature siliconepitaxial films, and films comprising silicon, silicon oxide, siliconoxynitride, silicon nitride, etc., as well as to corresponding processesfor forming such films with such precursors.

[0060] In one aspect, the invention provides as such precursor acompound of the formula:

[SiX_(n)(NR¹R²)_(3-n)]₂  (1)

[0061] wherein:

[0062] R¹ and R² may be the same as or different from one another andeach is independently selected from the group consisting of H, C₁-C₅alkyl, and C₃-C₆ cycloalkyl;

[0063] X is selected from the group consisting of halogen (e.g.,bromine, fluorine and chlorine), hydrogen and deuterium; and

[0064] 0≦n≦2.

[0065] One preferred class of compounds of formula (1) has the formula:

[0066] wherein R1 and R2 are as defined in connection with formula (1).

[0067] The compounds of formula (1) are usefully employed for formingfilms on substrates, e.g., by chemical vapor deposition at temperature<500° C. The films that can be formed using such precursor compoundsinclude low dielectric constant (k) thin films, high k gate silicatesand silicon epitaxial films. In one aspect of the invention, the filmsformed using such precursors comprise silicon, silicon oxide, siliconoxynitride and/or silicon nitride.

[0068] Preferred compounds of formula (1) include(Et₂N)₂ClSi—SiCl(NEt₂)₂, (EtNH)₃Si—Si(HNEt)₃,(Bu^(t)NH)₂ClSi—SiCl(HNBu^(t))₂, (Me₂N)₂ClSi—SiCl(NMe₂)₂, Cl₂HSi—SiHCl₂,(EtNH)₂HSi—SiH(NHEt)₂, and the like.

[0069] Compounds of formula (1) are readily synthesized by reaction ofdisilane compounds of the formula X₃Si—SiX₃ with amine (R¹R²NH) orlithium amide ((R¹R²N)Li compounds, wherein X, R¹ and R² are as set outabove, according to following reactions:

[0070] as hereinafter more fully described in the examples herein.

[0071] In specific applications, it may be necessary or desirable toconduct a second reaction to introduce hydrogen in place of the halogen.

[0072] The invention in another aspect provides a further class ofsilicon precursor compounds, comprising nitrogen-containing cyclosiliconcompounds of the formula:

[0073] wherein:

[0074] each of R₃ can be the same as or different from the other andeach is independently selected from the group consisting of H, C₁-C₄alkyl, and C₃-C₆ cycloalkyl; and

[0075] each of R₄, R₅ and R₆ can be the same as or different from theothers and each is independently selected from the group consisting ofH, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, Si(CH₃)₃ and SiCl₃.

[0076] A preferred class of compounds of formula (2) includes thecompounds of formula (2a):

[0077] wherein each of the R substituents may be the same as ordifferent from the other and each is independently selected from thegroup consisting of H, C₁-C₄ alkyl, and C₃-C₆ cycloalkyl. In onepreferred compound of such type, both R substituents are hydrogen. Inanother preferred compound of such type, both R substituents are methyl.

[0078] The precursors of formula (2a) contain two silicon atoms in afour-member ring structure with four tertiary butyl (Bu^(t)) groups onthe nitrogen atoms. In such compositions, as employed for chemical vapordeposition of silicon nitride, the tertiary butyl groups are effectiveleaving groups, so that there is minimal Bu^(t)-associated carbonincorporation into films formed from such precursors. In one preferredaspect of the invention, such precursors are usefully employed in lowtemperature (<500° C.) CVD processes as precursors for silicon nitridefilms.

[0079] With reference to the silicon compounds of formula (2a), anotherclass of compounds of the present invention includes those correspondingto formula (2a) but wherein the tertiary butyl (Bu^(t)) groups arereplaced by trimethylsilyl (—SiMe₃) or trichlorosilyl (—SiCl₃) groups.

[0080] The precursors of formulae (2) and (2a) can be advantageouslyemployed as ligands to form corresponding metal complexes, bydeprotonation reaction serving to remove the hydrogen substituents ofhydrogen-bearing groups, e.g., the tertiary butyl (Bu^(t)) groups on thenitrogen atoms in formula (2a), to form corresponding anionic species,followed by reaction of the anionic species with metal cations (whichcan be any metal or transition metal of the Periodic Table, e.g.,hafnium (Hf), zirconium (Zr), barium (Ba), etc.) to form correspondingneutral metal source reagent complexes. Such metal source reagentcomplexes are usefully employed as CVD precursors for metal nitrides,metal oxides and pure metal films.

[0081] The precursors of formula (2) and their corresponding metalcomplexes are usefully employed for forming thin films on substrates bychemical vapor deposition.

[0082] Another class of silicon precursors in accordance with theinvention, which are amenable to CVD use at low temperatures, such as inthe range of from about 350° C. to about 550° C. for pre and post metaldeposition of thin (e.g., 500 Angstroms to 1 micrometer thickness)dielectric films of silicon nitride or silicon dioxide in semiconductormanufacturing, or otherwise for forming silicon nitride or silicondioxide ceramic thin films as well as films on different substrates, attemperatures in the range of from about 100° C. to about 600° C.,comprise the disilicon cycloamides of the formulae (3)-(6):

[0083] wherein:

[0084] each of R₈ can be the same as or different from the others andeach is independently selected from the group consisting of H, C₁-C₄alkyl, and C₃-C₆ cycloalkyl; and

[0085] each of R₉ can be the same as or different from the others andeach is independently selected from the group consisting of H and NR₈Hwhere R₈ is as defined above.

[0086] Another class of compounds useful as silicon precursors in thepractice of the invention include those of formula (7):

[0087] wherein:

[0088] each of R₁₀ and R₁₁ can be the same as or different from theothers and each is independently selected from the group consisting ofH, C₁-C₄ alkyl, and C₃-C₆ cycloalkyl.

[0089] One preferred compound of those of formula (7) is thecyclosilicon compound wherein each of R₁₀ and R₁₁ is tertiary butyl(Bu^(t)).

[0090] The compounds of formulae (1)-(7) can be reacted with suitableco-reactants at relatively low activation energies, as for example inaccordance with the reaction scheme (C) shown below:

[0091] In reaction scheme (C), “Precursors” are any of the precursorcompounds of formulae (1)-(7). The co-reactant can be (i) oxygen, ozoneor CO₂ to form low k dielectric films, (ii) oxygen or a combination ofoxygen and nitrogen at deposition temperature <600° C. to form silicondioxide, (iii) ammonia “or A,” wherein “A” is selected from the groupconsisting of R₃Si—N₃, R—N═NR′ and R—N═N⁺═NR′, each R is independentlyselected from the group consisting of C₁-C₃ alkyl substituents, R′ is Ror H, and such co-reactant species is employed at deposition temperature<600° C. to form silicon nitride, (iv) dinitrogen oxide (nitrous oxide,N₂O), or a mixture of nitrous oxide and ammonia, at temperature <600°C., to form silicon oxynitride, (v) hydrogen and silane, for lowtemperature silicon epitaxy, and (vi) hafnium and/or zirconium sources,in the presence of oxygen and nitrous oxide, to form silicate gatestructures.

[0092] In accordance with reaction scheme (C), the type of dielectricfilm produced by the corresponding CVD process can be tailored by choiceof the specific co-reactant. For example, hydrogen, ammonia, oxygen ornitrous oxide may be used as alternative single reactants to form therespective silicon nitride, silicon dioxide or silicon oxynitride singlecomponent films, or a mixture of two or more of such reactants can beemployed in the CVD process with selected one(s) of the formulae (1)-(7)precursors to form corresponding multi-component films, or gradedcomposition films. Other co-reactants may be added to introduce otherelemental species (e.g., hafnium, zirconium, barium, titanium, tantalum,etc.).

[0093] In a further aspect, the invention relates to a method of forminga silicon epitaxial layer on a substrate at temperature below about 600°C., preferably less than about 550° C., by contacting the substrate witha silicon precursor in the presence of a substantial excess of areducing agent, e.g., a reducing agent such as hydrogen, silane (SiH₄),disilane (Si₂H₆), etc.

[0094] A further aspect of the invention relates to the use of siliconsource compounds with nitrogen source compounds other than nitrogen orammonia that afford lower activation energy formation of silicon nitrideon a substrate, at temperatures <550° C. The use of such alternativeco-reactant nitrogen source compounds overcomes the difficulty ofdepositing silicon nitride at reasonable deposition rates at temperaturebelow 550° C. due to the high activation energy required for nitrogen orammonia to form Si—N bonds in such low temperature regime.

[0095] The use of low activation energy co-reactant nitrogen sourcecompounds permits silicon source compounds that would otherwise beunacceptable in use with ammonia or nitrogen, to be efficiently employedto deposit silicon-containing and nitrogen-containing films attemperatures <550° C. Low activation energy co-reactant nitrogen sourcecompounds for such purpose can be of any suitable type, including forexample R-diazo compounds, wherein R is H, C₁-C₄ alkyl or C₃-C₆cycloalkyl, triazoles and tetrazoles, amadines, silylazides, small ringnitrogen compounds such as aziridines, or molecules including organicacyclic or cyclic moieties that contain one or more —N—N bonds.

[0096] In use, co-reactants of the foregoing types are introduced to theCVD reactor as reactive gases, along with the silicon sourcecompound(s). Co-reactant reactive gases of such types, comprisingcompounds that contain multiple nitrogen atoms, can be used withreactive disilanes such as hexachlorodisilane that would otherwise bewholly unsuitable for formation of silicon nitride films at temperatures<550° C. In such usage, particulate formation is controlled underoptimized CVD process conditions to eliminate particle-generatinghomogenous gas-phase reactions.

[0097] In application of the co-reactant reaction scheme (C), thesilicon-containing precursor is reacted with a desired co-reactant inany suitable manner, e.g., in a single wafer CVD chamber, or in afurnace containing multiple wafers, utilizing process conditionsincluding temperature <550° C. and appertaining pressures,concentrations, flow rates and CVD techniques, as readily determinablewithin the skill of the art for a given application, based on thedisclosure herein.

[0098] By way of example, in the application of such co-reactant scheme,silicon nitride films can be deposited by deposition techniques such asatomic layer deposition (ALD) involving sequenced pulses wherein the twoor more reactants are sequentially introduced to react on the surfacebearing the adsorbed reactant species, to form one monolayer of the SiNfilm at a time.

[0099] Alternatively, silicon nitride films can be formed bylow-pressure CVD techniques, e.g., by a single-wafer deposition processat pressure in a range of from about 1 to about 1000 torr, or in a batchdeposition furnace procedure at low pressure such as pressure ≦4 torr,involving chemical reactions that take place in a pressure range of fromabout 100 mtorr to 4 torr.

[0100] An illustrative low-pressure chemical vapor deposition (LPCVD)process is described below.

[0101] In the first step of such illustrative LPCVD process, reactantsare introduced into the reaction chamber. Such reactants can be dilutedwith inert gases, if and as needed, to facilitate reaction control andhomogeneous mixing. The reactants are diffused onto the substrate andare adsorbed on the substrate surface.

[0102] In a second step of the LPCVD process, the reactants adsorbed onthe substrate undergo migration and/or chemically react on the surface,with gaseous byproducts of the reaction being desorbed to leave behindthe deposited film.

[0103] The co-reactant deposition may be carried out to form siliconnitride, silicon dioxide or silicon oxynitride films in any suitablereactor, e.g., a vertical flow isothermal LPCVD reactor. A verticalreactor is usefully employed to avoid wafer-to-wafer reactant depletioneffects; such reactor does not require temperature ramping, and produceshighly uniform deposited films.

[0104] The vacuum system utilized for providing the low pressurecondition of the LPCVD process can be of any suitable type, and can forexample include a dry pump or rotary vane pump/roots blower combinationand various cold traps if and as needed. Reactor pressure can becontrolled by a capacitance manometer feedback to a throttle valvecontroller.

[0105] Use of a conventional LPCVD system to carry out reactions of theco-reactant scheme (C), at reactor loadings of eighty 200 or 300 mmdiameter silicon wafers at 4-9 mm spacing, produced a uniformconductance around the wafer peripheries by compensating for conductancerestrictions attributable to the boats and the sled in such system. Thetemperature uniformity across the wafer load was ±1° C. as measured byan internal multi-junction thermocouple. Deposition uniformity down thewafer load was improved by employing a temperature ramp. Changing thereactant to precursor ratios from 100:1 to 1:1 optimized depositionconditions. The pressure was typically below 1 torr, being varied from100 mtorr to 1 torr, and the optimum deposition temperature was in arange of from about 100° C. to about 550° C. In general, the inventionmay be carried out with delivery of precursors in neat form, via liquiddelivery, or bubbler or vaporizer. Solvents can be employed for liquiddelivery, such as organic solvents, e.g., amine solvents such asNR_(x)H_(3-x), wherein R is H or C₁-C₄ alkyl, etc.

[0106] As another example of specific precursors useful in the generalpractice of the invention to form silicon-containing films, such assilicon, silicon oxide, silicon nitride, and silicon oxynitride films,silicate gate materials and low k dielectrics,tetrakisdiethylamidodichlorodisilane, (NEt₂)₂ClSi—SiCl(NEt₂)₂ is aprecursor containing a silicon-silicon bond with only two chlorines inthe molecule, and amido groups which are efficient leaving groups in theformation of silicon-containing films having a low carbon contaminationcharacteristic.

[0107] Tetrakisdiethylamidodichlorodisilane is readily synthesized ashereinafter more fully described in Example 5 hereof, and is usefullyemployed to form silicon-containing films of good quality, such as filmsof silicon, silicon oxide, silicon nitride, silicon oxynitride, etc., bylow pressure CVD.

[0108] The features and advantages of the invention are more fully shownby the following illustrative and non-limiting examples.

EXAMPLE 1 Synthesis of (HNEt)₃Si—Si(HNEt)₃

[0109] In a 5 L flask, 152 g (0.565 mol) of Cl₃SiSiCl₃ was added with 4L of hexanes. The flask was cooled to 0° C. using an ice-bath. EtNH₂(400 g, 8.87 mol; b.p.32° C.) was added to the flask under magneticstirring. White precipitate material was observed immediately. Uponcompletion of the addition, the ice-bath was removed and the flask wasallowed to warm up to room temperature. The reaction mixture was keptstirring overnight and then refluxed for another two hours. After thereaction mixture was cooled to room temperature, it was filtered througha glass frit filter. The solvent was removed from the filtrate undervacuum. Crude product (152 g) was obtained (84% yield). The pure product((HNEt)₃Si—Si(HNEt)₃) was obtained from fractional distillation at about95° C. under 120 mtorr. Shown in FIGS. 1 and 2 are the ¹H— and ¹³C-NMRspectra respectively. FIG. 3 shows the STA data. ¹H NMR (C₆D₆): δ 0.67(br, 6H, N-H)1.07 (t, 18H), 2.91 (p, 12H); ¹³C {¹H} NMR (C₆D₆): δ 0.67(CH₂); C₁₂H₃₆N₆Si₂ Calcd: C, 44.95; H, 11.32; N, 26.21; Found: C, 44.69;H, 10.75; N, 25.85.

[0110] The STA data showed the T₅₀ value of (HNEt)₃Si—Si(HNEt)₃ to beabout 185° C., evidencing good volatility and transport properties forchemical vapor deposition.

EXAMPLE 2 Synthesis of (Bu^(t)NH)₂ClSi—SiCl(HNBu^(t))₂

[0111] In a 250 mL flask with 180 mL of diethyl ether, 5 g (18.6 mmol)of Cl₃SiSiCl₃ was added. The flask was cooled to 0° C. in an ice-bath.Under magnetically stirring, Bu^(t)NH₂ (13.6 g/186 mmol) in 30 mL ofether was added into the flask dropwise. White precipitate material wasformed immediately. Upon completion of the addition, the ice-bath wasremoved and the flask was allowed to warm up to room temperature. Thereaction mixture was stirred overnight and then refluxed for another twohours. After the reaction mixture was cooled to room temperature, it wasfiltered through a frit filter. Removal of volatiles from the filtrategave 6.10 g of white solid crude product in 79% yield. It can furtherpurified by recrystallization from its hexanes-THF mixture solution at0° C. The crystals have been characterized by X-ray analysis. Shown inFIGS. 4 and 5 are the ¹H- and ¹³C-NMR spectra, respectively. FIG. 6shows the STA data for the product, (Bu^(t)NH)₂ClSi—SiCl(HNBu^(t))₂,which had a T₅₀ value of about 196° C., evidencing good volatility andtransport properties for chemical vapor deposition.

[0112]¹H NMR (C₆D₆): δ 1.28 (s, 36H), 1.59 (br, 4H, N—H), ¹³C {¹H} NMR(C₆D₆): δ 33.4 (CH₃), 50.8 (C); C₁₆H₄₀Cl₂N₄Si₂ Calcd: C, 46.24; H, 9.70;N, 13.48; Found: C, 45.98; H, 9.99; N, 13.14.

EXAMPLE 3 Synthesis of (Bu^(t)NH)₂Si(H)Cl

[0113] The general reactions were carried out under a steady flow ofnitrogen. A 500 mL Schlenk flask equipped a magnetic stirring bar, wascharged with 250 mL of dry ether and 21.6 g of ^(t)BuNH₂ and. To thisflask, 10 g, 73.8 mmol of HSiCl₃ in 50 mL of ether was added dropwise at0° C. Upon completion of the addition, the mixture was stirredovernight. The mixture was then refluxed for an additional 4 hours. Itwas cooled to room temperature and filtered through Celite®. Solventswere removal of by quick distillation or vacuum. The crude yield was80%. It was then purified by fractional vacuum distillation to around98% in purity. The product, (Bu^(t)NH)₂Si(H)Cl, was characterized bysolution NMR in C₆D₆ (FIG. 7). ¹H NMR (C₆D₆), δ (ppm), 5.48 (t, 1H),1.09 (s, 18H).

EXAMPLE 4 Synthesis of η-(N,N-t-butyl)-di(t-butylamino)cyclodisilane

[0114] The general reactions were carried out under a steady flow ofnitrogen using Schlenk techniques. A 250 mL Schlenk flask was chargedwith 9.22 g, 44.2 mmol of di(tert-butylamino)(chloro)silane in 150 mL ofhexanes and a stir bar. Then 26 mL of 1.7 M tert-butyllithium solutionin patane was added into the Schlenk flask slowly at 0° C., undermagnetic stirring. A white precipitate of LiCl formed during theaddition. Upon completion of the addition, the mixture was refluxedovernight. The reaction mixture was then allowed to cool and filteredthrough Celite® to obtain a slightly yellow clear solution. Allvolatiles were removed under vacuum and the crude yield was about 60%.This crude product was purified by vacuum column distillation. The pureproduct was received while the oil bath temperature was set to 170° C.and the vacuum at 200 mtorr. It was characterized by solution NMR inC₆D₆ (FIG. 8) and STA (FIG. 9). ¹H-NMR (C₆D₆), δ (ppm), 5.31 (dd, 2H,cis or trans isomer), 5.12 (d, 2H, cis or trans isomers), 1.42 (s, 18H,cis or trans isomer), 1.41 (s, 18H, cis or trans isomer) and 1.24 (s,18H, both isomers).

EXAMPLE 5 Synthesis of (NEt₂)₂ClSiSiCl(NEt₂)₂

[0115] In a 250 mL flask with 180 mL of ether, 5 g, 18.6 mmol ofCl₃SiSiCl₃ was added. The flask was cooled to 0° C. using an ice-bath.While kept stirring, Et₂NH₂, 16.3 g, 223 mmol in 30 mL of ether wasadded dropwise into the flask. Upon completion of addition, the ice-bathwas removed and the flask was allowed to warm up to room temperature.The reaction mixture was kept stirring overnight and then refluxed foranother two hours. After the reaction mixture was cooled to roomtemperature, it was filtered through a frit filter. The solvent wasremoved from the filtrate by vacuum. The producttetrakisdiethylamidodichlorodisilane was obtained from columndistillation while controlling the oil bath temperature at around 165°C. 6.35 g, 15.2 mmol product, (NEt₂)₂ClSiSiCl(NEt₂)₂, was obtained whichcorresponded to 82% yield. ¹H NMR in C₆D₆: 1.05 (t, 16H), 3.02 (q, 24H).C₁₆H₄₀Cl₂N₄Si₂ Calcd: C, 46.24; H, 9.70; N, 13.48; Found: C, 46.17; H,9.73; N, 13.33.

EXAMPLE 6 Silicon Nitride Deposition From (HNEt)₃Si—Si(HNEt)₃

[0116] A solution of the compound of Example 1, (HNEt)₃Si—Si(HNEt)₃, wasprepared at a concentration of 0.4M in a hydrocarbon solvent. Thissolution was metered at 0.1 ml/minute into a vaporizer that was held attemperature of 120° C. and had a flow of 10 standard cubic centimetersper minute (sccm) of He as a carrier gas. The vapor was mixed with 10sccm of NH₃ in a showerhead vaporizer device that was maintained at 120°C. and thereby dispersed over the surface of a heated Si(100) wafer. Thechamber pressure was maintained at 10 torr during deposition. The growthrate of the silicon nitride films decreased from 470 Å/minute at a wafertemperature of 625° C. to 26 Å/minute at 450° C. as shown in FIG. 10.

[0117] Chemical analysis of the films, by a combination of RBS(Rutherford Backscattering), HFS (Hydrogen Forward Scattering), and NRA(Nuclear Reaction Analysis), revealed that higher pressures and higherNH₃ flows increased the N/Si ratio to the stoichiometric value of 1.33and decreased the impurity carbon content as shown in Table 1 below.TABLE 1 Film composition for various deposition conditions using theprecursor (HNEt)₃Si—Si(HNEt)₃. Rate NH3 T P (Å/ H C O (sccm) (° C.)(torr) min) n (at %) (at %) (at %) N/Si 10 550 10 196 1.87 20.5 13.513.3 1.15 100 530 40 72 1.78 25.5 5.2 11.2 1.31 100 530 80 59 1.79 21.55 5.9 1.37 140 624 80 184 1.84 14.5 3.6 0.9 1.36

EXAMPLE 7 Silicon Nitride Deposition with a Pulsed Process From(HNEt)₃Si—Si(HNEt)₃

[0118] (HNEt)₃Si—Si(HNEt)₃ was vaporized continuously at a rate of 100μmol/minute at 120° C. with 10 sccm of He carrier gas and directedeither to the deposition process or to a process bypass. NH₃ wassupplied continuously to the process at 10 sccm.

[0119] During the periods when precursor was directed to the process,the NH₃ was activated only by the temperature of the wafer surface. Anincreased transmissive optical frequency range was observed, indicatinga higher band gap, when the precursor supply time to the wafer wasdecreased relative to the precursor supply time to the bypass.Alternatively, during the periods where the precursor was directed tothe bypass, a hot filament network above the wafer surface was heated tosupplement the activation of the NH₃. The filament either was made oftungsten and held at 2000K or it was made of Pt and held at 600° C.

[0120] The period of time during which the precursor was directed at theprocess was enough to deposit at least a few monolayers. The period oftime during which the precursor was directed to bypass was enough toincrease the N:Si ratio to above 1.3. The NH₃ supply was constantlydirected to the chamber, or diverted to bypass when the precursor wassupplied to the wafer surface. Additionally, during the time when theprecursor was directed to bypass, the chamber pressure was able to beincreased to substantially higher than the deposition pressure (e.g.,100 Torr). The precursor and pulsed nitrogen source were also able to beseparated temporally.

EXAMPLE 8 Silicon Nitride Deposition From (NEt₂)₂ClSi—SiCl(NEt₂)₂

[0121] A solution of the compound of Example 5, (NEt₂)₂ClSi—SiCl(NEt₂)₂,was prepared at a concentration of 0.4M in a hydrocarbon solvent. Thissolution was metered at 0.2 ml/minute into a vaporizer that wasmaintained at temperature of 120° C. and had a flow of 10 sccm of He asa carrier gas. The vapor was mixed with 10 sccm of NH₃ in a showerheadvapor disperser device that was held at temperature of 120° C., andthereby dispersed over the surface of a heated Si(100) wafer. Thechamber pressure was maintained at pressure of 10 torr duringdeposition. The growth rate of the silicon nitride films decreased from650 Å/minute at a wafer temperature of 625° C. to 9 Å/minute at 450° C.,as shown in FIG. 11. (The index of refraction, n, was >2.2 in all cases,and some films contained Cl.)

EXAMPLE 9 Silicon Nitride Deposition FromCyclotrimethylene-bis(t-butylamino)silane

[0122] A solution of the compoundcyclotrimethylene-bis(t-butylamino)silane was prepared at aconcentration of 0.4M in a hydrocarbon solvent. This solution wasmetered at 0.2 ml/minute into a vaporizer that was maintained attemperature of 120° C. and had a flow of 10 sccm of He as a carrier gas.The vapor was mixed with 10 sccm of NH₃ in a showerhead vapor disperserthat was held at temperature of 120° C. and thereby dispersed over thesurface of a heated Si(100) wafer. The chamber pressure was maintainedat 2, 5, or 10 torr during deposition. The growth rate of the siliconnitride films decreased from 53 Å/minute at a wafer temperature of 625°C. to 9 Å/minute at 575° C. as shown in FIG. 12. There was no measurableeffect of pressure on the growth rate, however, which increased from1.65 to 1.73 as the pressure decreased from 10 torr to 2 torr at 575° C.

EXAMPLE 10 Silicon Nitride Deposition Fromη-(N,N-t-butyl)-di(t-butylamino)cyclodisilane

[0123] A solution of the compound of Example 4,η-(N,N-t-butyl)-di(t-butylamino)cyclodisilane, was prepared at aconcentration of 0.4M in a hydrocarbon solvent. This solution wasmetered at 0.2 ml/minute into a vaporizer that was held at 120° C. andhad a flow of 10 sccm of He as a carrier gas. The vapor was mixed with10 sccm of NH₃ in a showerhead vapor disperser that was held at 120° C.and the vapor was thereby dispersed over the surface of a heated Si(100)wafer. The chamber pressure was maintained at 10 torr during deposition.The growth rate of the silicon nitride films decreased from 15 Å/minuteat a wafer temperature of 625° C. to 2 Å/minute at 575° C. as shown FIG.13.

[0124] While the invention has been described herein with reference tovarious specific embodiments, it will be appreciated that the inventionis not thus limited, and extends to and encompasses various othermodifications and embodiments, as will be appreciated by thoseordinarily skilled in the art. Accordingly, the invention is intended tobe broadly construed and interpreted, in accordance with the ensuingclaims.

What is claimed is:
 1. A silicon compound selected from the groupconsisting of: (A) compounds of the formula:[SiX_(n)(NR¹R²)_(3-n)]₂  (1)  wherein: R¹ and R² may be the same as ordifferent from one another and each is independently selected from thegroup consisting of H, C₁-C₅ alkyl, and C₃-C₆ cycloalkyl; X is selectedfrom the group consisting of halogen, hydrogen and deuterium; and 0≦n≦2;(B) compounds of the formula (2)

 wherein: each of R₃ can be the same as or different from the other andeach is independently selected from the group consisting of H, C₁-C₄alkyl, and C₃-C₆ cycloalkyl; and each of R₄, R₅ and R₆ can be the sameas or different from the others and each is independently selected fromthe group consisting of H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, Si(CH₃)₃ andSiCl₃; (C) metal source reagent complexes formed by metal cationreaction with deprotonated anionic forms of the compounds (B); (D)disilicon cycloamides of the formulae (3)-(6):

 wherein: each of R₈ can be the same as or different from the others andeach is independently selected from the group consisting of H, C₁-C₄alkyl, and C₃-C₆ cycloalkyl; and each of R₉ can be the same as ordifferent from the others and each is independently selected from thegroup consisting of H and NR₈H where R₈ is as defined above; and (E)cyclosilicon compounds of the formula:

wherein: each of R₁₀ and R₁₁ can be the same as or different from theothers and each is independently selected from the group consisting ofH, C₁-C₄ alkyl, and C₃-C₆ cycloalkyl.
 2. A silicon compound of theformula [SiX_(n)(NR¹R²)_(3-n)]₂  (1)  wherein: R¹ and R² may be the sameas or different from one another and each is independently selected fromthe group consisting of H, C₁-C₅ alkyl, and C₃-C₆ cycloalkyl; X isselected from the group consisting of halogen, hydrogen and deuterium;and 0≦n≦2.
 3. The silicon compound of claim 2, selected from the groupconsisting of (Et₂N)₂ClSi—SiCl(NEt₂)₂, (EtNH)₃Si—Si(HNEt)₃,(Bu^(t)NH)₂ClSi—SiCl(HNBu^(t))₂, (Me₂N)₂ClSi—SiCl(NMe₂)₂, Cl₂HSi—SiHCl₂,and (EtNH)₂HSi—SiH(NHEt)₂.
 4. The silicon compound of claim 2, of theformula:


5. A silicon compound of the formula (2):

wherein: each of R₃ can be the same as or different from the other andeach is independently selected from the group consisting of H, C₁-C₄alkyl, and C₃-C₆ cycloalkyl; and each of R₄, R₅ and R₆ can be the sameas or different from the others and each is independently selected fromthe group consisting of H, C₁-C₄ alkyl, C₃-C₆ cycloalkyl, Si(CH₃)₃ andSiCl₃.
 6. The silicon compound according to claim 5, selected from thegroup consisting of compounds of the formula:

wherein each of the R substituents may be the same as or different fromthe other and each is independently selected from the group consistingof H, C₁-C₄ alkyl, and C₃-C₆ cycloalkyl; and metal source reagentcomplexes formed by metal cation reaction with deprotonated anionicforms of the compounds of formula (2a).
 7. The silicon compound of claim6, wherein both R substituents are hydrogen.
 8. The silicon compound ofclaim 6, wherein both R substituents are methyl.
 9. The silicon compoundof claim 6, of the formula (2a).
 10. The silicon compound of claim 6,comprising a metal source reagent complex formed by metal cationreaction with a deprotonated anionic form of a compound of formula (2a).11. The silicon compound of claim 10, wherein the metal cation comprisesa cation of a transition metal.
 12. The silicon compound of claim 10,wherein the metal cation comprises a cation of a metal selected from thegroup consisting of hafnium (Hf), zirconium (Zr), and barium (Ba).
 13. Asilicon compound selected from the group consisting of disiliconcycloamides of the formulae (3)-(6):

wherein: each of R₈ can be the same as or different from the others andeach is independently selected from the group consisting of H, C₁-C₄alkyl and C₃-C₆ cycloalkyl; and each of R₉ can be the same as ordifferent from the others and each is independently selected from thegroup consisting of H and NR₈H where R₈ is as defined above.
 14. Acyclosilicon compound of the formula:

wherein: each of R₁₀ and R₁₁ can be the same as or different from theothers and each is independently selected from the group consisting ofH, C₁-C₄ alkyl, and C₃-C₆ cycloalkyl.
 15. The silicon compound of claim14, wherein each of R₁₀ and R₁₁ is tertiary butyl (Bu^(t)). 16.(NEt₂)₂ClSi—SiCl(NEt₂)₂.
 17. A method of forming a silicon-containingfilm on a substrate, comprising contacting a substrate under chemicalvapor deposition conditions including temperature below 600° C. with avapor of a silicon compound as in claim
 1. 18. The method of claim 17,wherein the silicon compound is of formula (1).
 19. The method of claim18, wherein the silicon-containing film comprises a material selectedfrom the group consisting of silicon oxide, silicon oxynitride andsilicon and said temperature is <500° C.
 20. The method of claim 19,wherein the silicon-containing compound is selected from the groupconsisting of (Et₂N)₂ClSi—SiCl(NEt₂)₂, (EtNH)₃Si—Si(HNEt)₃,(Bu^(t)NH)₂ClSi—SiCl(HNBu^(t))₂, (Me₂N)₂ClSi—SiCl(NMe₂)₂, Cl₂HSi—SiHCl₂,and (EtNH)₂HSi—SiH(NHEt)₂.
 21. The method of claim 19, wherein thesilicon-containing compound comprises a compound of the formula:


22. The method of claim 17, wherein the silicon compound comprises acompound of formula (2).
 23. The method of claim 17, wherein the siliconcompound is selected from those of the group consisting of compounds offormulae (3)-(6).
 24. The method of claim 17, wherein the siliconcompound comprises a compound of formula (7).
 25. The method of claim17, wherein said silicon-containing film comprises a film selected fromthe group consisting of films comprising silicon, silicon nitride(Si₃N₄), siliconoxynitride (SiO_(x)N_(y)), silicon dioxide (SiO₂), lowdielectric constant (k) thin silicon-containing films, high k gatesilicate films and low temperature silicon epitaxial films.
 26. Themethod of claim 17, wherein said chemical vapor deposition conditionscomprise temperature of from about 400 to about 625° C., pressure offrom about 10 to about 100 torr, and the presence of ammonia.
 27. Themethod of claim 17, wherein said chemical vapor deposition conditionscomprise temperature of from about 525 to about 625° C., pressure offrom about 0.1 to about 10 torr.
 28. The method of claim 17, comprisingdepositing oxynitride deposition of silicon.
 29. The method of claim 17,comprising depositing oxynitride deposition of silicate.
 31. The methodof claim 17, wherein the silicon-containing film comprises siliconnitride.
 32. The method of claim 17, wherein said temperature is <500°C.
 33. A method of making a compound of the formula:[SiX_(n)(NR¹R²)_(3-n)]₂  (1) wherein: R¹ and R² may be the same as ordifferent from one another and each is independently selected from thegroup consisting of H, C₁-C₅ alkyl, and C₃-C₆ cycloalkyl; X is selectedfrom the group consisting of halogen, hydrogen and deuterium; and 0≦n≦2,said method comprising reacting a disilane compound of the formulaX₃Si—SiX₃ with an amine (R¹R²NH) or lithium amide ((R¹R²N)Li compound,wherein X, R¹ and R² are as set out above, according to a reactionselected from the group consisting of the following reactions:

wherein each of the R substituents may be the same as or different fromthe other and each is independently selected from the group consistingof H, C₁-C₄ alkyl, and C₃-C₆ cycloalkyl.
 34. A method of forming ametal, metal nitride or metal oxide film on a substrate, comprisingcontacting said substrate with a precursor metal complex formed by ionicreaction of metal cation with a deprotonated compound formed bydeprotonation reaction of a silicon compound of formula (2) as inclaim
 1. 35. The method of claim 34, wherein said silicon compound hasthe formula:

wherein each of the R substituents may be the same as or different fromthe other and each is independently selected from the group consistingof H, C₁-C₄ alkyl, and C₃-C₆ cycloalkyl.
 36. The method of claim 34,wherein the metal cation comprises cation of a metal selected from thegroup consisting of hafnium, zirconium and barium.
 37. The method ofclaim 17, wherein the silicon compound comprises a disilicon cycloamidecompound.
 38. The method of claim 17, wherein the silicon compoundcomprises a precursor reacted with a co-reactant in a reaction schemeselected from the group consisting of those of reaction scheme (C)below:

wherein A is selected from the group consisting of R₃S₁—N₃, R—N═NR′ andR—N═N⁺═NR′, wherein each R is independently selected from the groupconsisting of C₁-C₃ alkyl and R′ is R or H.
 39. The method of claim 38,wherein the silicon compound comprises (NEt₂)ClSi—SiCl(NEt₂).
 40. Amethod of forming a silicon nitride film on a substrate by chemicalvapor deposition, comprising contacting said substrate with vapor ofsilicon source and nitrogen source compounds, wherein said nitrogensource compounds are other than nitrogen or ammonia, and said chemicalvapor deposition is conducted at temperature <550° C., wherein saidnitrogen source compound is selected from the group consisting ofR-diazo compounds, wherein R is H, C₁-C₄ alkyl or C₃-C₆ cycloalkyl,triazoles, tetrazoles, amadines, silylazides, small ring nitrogencompounds, and molecules including organic acyclic or cyclic moietiesthat contain one or more —N—N bonds.
 41. The method of claim 40, whereinsaid small ring nitrogen compounds are selected from the groupconsisting of aziridines.
 42. A method of forming a silicon epitaxiallayer on a substrate at temperature below about 600° C., by contactingthe substrate with a silicon precursor in the presence of a substantialexcess of a reducing agent.
 43. The method of claim 42, wherein saidreducing agent comprises an agent selected from the group consisting ofhydrogen, silane (SiH₄) and disilane (Si₂H₆).
 44. The method of claim43, wherein the temperature is below about 550° C.